Plugging system for extrusion containers



April 30, 1968 c. SAUVE 3,380,270

PLUGGING SYSTEM FOR EXTRUSION CONTAINERS Filed June 23, 1965 2Sheets-Sheet 1 April 30, 1968 c. SAUVE 3,380,270

PLUGGING SYSTEM FOR EXTRUSION CONTAINERS Filed June 23, 1965 2Sheets-Sheet 2 United States Patent @fice 3,380,270 PLUGGING SYSTEM FOREXTRUSIGN CONTAINERS Charles Sauve, Versailles, France, assignor toCommissariat a lEnergie Atomique, Paris, France Filed June 23, 1965,Ser. No. 466,225 Claims priority, appligcatigrz gl rance, July 3, 1964,

3 Claims. (or. 7245 ABSTRACT OF THE DESCLOSURE This invention relates toa plugging system for extrusion containers whereby a container of thistype can in particular be temporarily closed oft on the one hand on thefront side of its die and on the other hand at the rear end of the bodyor billet to be extruded which is placed within said container, namelybetween said body and an extrusion ram. The primary object of saidsystem is to ensure a uniform distribution of a lubricating materialwhich has been previously introduced within the container so as tosurround the billet entirely between this latter and the container wall.

The underlying principle of an extrusion method of this type andspecifically of the lubrication process referred-to has already beendescribed in US. Patent No. 3,072,251 as filed by Commissariat alEnergie Atomique, wherein the apparatus employed was designed for usein conjunction with obturators or shutters consisting of metal partshaving suitable mechanical strength, the rear shutter being formed by astamped plate, the edges of which are applied by the pressure of thelubricant against the walls,

of the extrusion container, whereas the front shutter consists of asmall plate which is held in position between the die and the die-holderand is designed to fail under the pressure exerted by the billet at thecommencement of the extrusion process proper.

By reason of their very nature and design, obturators or shutters of thetype referred-to above have to be replaced at the end of each extrusionoperation. As can be understood, it is therefore of interest to replacesuch obturators by another sealing system consisting of removablemembers which can either be positioned or withdrawn at predeterminedmoments, on the one hand in front of the die and on the other handbehind the body to be extruded, one particular result thereby achievedbeing to permit of suitable injection and distribution of the lubricantwithin the extrusion container. Accordingly, it is possible inparticular to employ on the one hand a simple front plug which isadapted to engage to a slight extent within the end of the die and, onthe other hand, a rear plug which is connected in leak-tight manner tothe extrusion ram without preventing this latter from sliding within thecontainer for performing the extrusion operation proper. Preferably, andin a manner which is well known to those skilled in the art, said rearplug consists of a metal block designed to slide along the stem of theextrusion ram with interposition of packing glands, said block beingfitted with means for applying this latter in leak-tight manner againstthe extremity of the extrusion container, preferably in synchronism withthe movement of displacement of the ram.

3,38%,270 Patented Apr. 30, 1968 The object of this invention is toimprove the arrangements noted above, in particular by making itpossible to ensure that hydrostatic pressure of the lubricant ismaintained within the extrusion container while the rear plug is appliedat the same time against the extremity of said container during theentire movement of displacement of the ram which effects the extrusionoperation.

To this end, the improvement proposed mainly consists in utilizing therelative motion of the ram rod and the metal block which constitutes therear plug for the purpose of effecting an injection of lubricant undervery high pressure into the extrusion container, said lubricant beingpreferably maintained in the plastic state and at a suitable temperatureinside an annular feed reservoir which is formed between the ram rod onthe one hand and the metal block on the other hand.

Under these conditions, the rear portion of the ram rod which has alarger diametrical cr0ss-secti0n serves to force the lubricant out ofits reservoir towards the interior of the extrusion container afterapplication of the rear plug and at a suitable pressure, the quantity oflubricant injected being exactly the quantity which is necessary for thepurpose of filling under the desired extrusion conditions, the spacewhich is left free between the internal Wall of said container and thebody to be extruded. The injection of lubricant is effected at thepressure of extrusion of the body to be extruded, the volume oflubricant injected being very small if it is compared with that whichwould be necessary in order to fill the chamber if no ram at all werepresent. In any case, the ram has the intended function of thrusting thebillet into its position of readiness for extrusion in contact with thedie, the injection of lubricant being thus performed partly at themoment when the billet is in the extrusion position after bein thrusttherein by the ram.

Consequently, the ram rod moves relatively to the rear plug to an extentwhich is equal to the displacement within the container as required forextrusion, and as increased to an extent which is necessary for thepreliminary injection of a given quantity of lubricant.

All of the above features will become more readily apparent from aperusal of the following description of one example of embodiment whichis given by way of indication and not in any limiting sense.

In the accompanying drawings, FIGS. 1, 2, 3 and 4 are diagrammatic viewsin partial cross-section of a horizontal extrusion press which entailsthe application of the improvement considered.

As can be seen from FIG. 1, the press which is illustrated comprises aheader 1 which serves to hold in position by means of a support member 2a die-holder 3 for a die 4; said die is placed at the end of the cavity5 of an extrusion container 6.

The preliminary closure at the front end of the die 4 is effected bymeans of a removable plug 7 which can be withdrawn at the beginning ofthe extrusion operation by any suitable means. As to the other end ofthe cavity 5, the closure means consist of a metal block 8, thecorresponding end of which is adapted to fit within a conical flare 9formed in the end of the cavity 5.

The rod 10 of a ram 11 is adapted to pass axially through the metalplugging block 8 and is extended towards the right hand side of thedrawing by a portion 12 having a transverse cross-section which isslightly larger than that of the central portion of the rod. Inside theblock 8, there is accordingly formed around said rod 16 an annularrecess 13 which can be filled with a quantity of suitable lubricantintroduced through an admission duct 14 formed through the body of theblock 8. The complete or partial filling of the annular space 13 by thelubricant is obtained by means of a high pressure pump (not shown in thedrawings) which comes into action when the ram 3 and the rear block 8are in the open position which is shown in FIG. 1.

In FIG. 1, the different members referred-to above are shown in theposition corresponding to the beginning of an operation involving theextrusion of a body or billet 15 which is carried in a cradle support16.

In a first step, the billet 15 is thrust into the cavity 5 of thecontainer 6 under the action of the ram 11 as this latter moves forwardtogether with the metal block 8 which forms a rear plug. When theforward end of the plug 8 engages within the conical portion 9 of thecavity 5 and thus effects the closure of this latter, the billet 15 isthrust forward by the ram 11 and thus brought into a position such thatthe front face of said billet is located at a distance of a fewcentimeters from the die 4, as shown in FIG. 2.

In a second step, a suitable pressure is applied to the metal block =8by conventional means (not shown) which can either be jacks secured tothe press header, screwtype breech-blocks, or any other device designedto ensure leak-tightness between the block and the extrusion container6. Then, in a third step, the ram 11 continues to move from the righthand side to the left hand side in the drawing and, during the initialpart of this movement, causes the lubricant to fill the entire spacewhich is left free between the billet 15 and the internal wall of thecavity 5, as shown in FIG. 3. The injection of lubricant takes placeunder the effect of the movement of the portion 12 of the end of the ramrod within the annular space 13. It should be noted that, at this stageof operations, the pressure at which the lubricant is injected ismaintained by the front plug 7 which is placed in front of the die andwhich therefore closes off said die in a leak-tight manner.

In a fourth step, as the forward movement of the ram 11 proceeds, theram places the billet l5 opposite the die 4. The extrusion processproper commences at this moment at the same time as the plug 7withdraws. During these operations, the lubricant continues to beinjected at very high pressure as a result of the forward displacementof the ram.

Finally, in a fifth step, when a sufiicient quantity of lubricant hasbeen injected into the cavity 5, a by-pass system (not shown in thedrawings) permits the evacuation of excess lubricant while the quantitywhich is necessary for the extrusion process itself continues to beinjected into the extrusion container at the pressure which is requiredin .order to force the metal through the die, as shown in FIG. 4.

It should be noted that, in the example described above, the sealsemployed, in particular for the purpose of providing leak-tightnessbetween the metal block which forms a rear plug and the different partsof the ram rod are sliding seals having good mechanical properties forthe purpose of affording resistance both to attrition and to heat. As anadvantageous feature, the seals employed consist of O-ring seals formedof stamped metal members which have a sufiicient degree of elasticity toallow the liquid lubricant to flow in one direction only. With thisobject in view, the rubbing portions .of said seals are preferablyformed of a metal which is softer than the steel of which the extrusioncontainer and the ram rod are usually fabricated. As another preferablefeature, said Oring seals can consist of two or a number of layers ofbonded metals, the outer layer having suitable mechanicalcharacteristics for the purpose of ensuring a good contact with thesteel whilst the inner layer is formed of a metal having a higher yieldstrength at operating temperatures.

Finally, it is of interest to mention the notable resistance of theextrusion container to tangential stresses which could otherwise resultin fast fracture. The hydrostatic pressures which are usually developedin conventional extrusion processes could in fact attain 12,000 to15,000 bars.

As will be readily understood, the invention is not limited in any senseto the form of embodiment which has been described and illustratedherein and which has been given solely by way of example.

What I claim is:

1. An extrusion device comprising an extrusion container, a cylindricalchamber opening through said container containing the body to beextruded, a die at .one end of said chamber, an extrusion ram, a ramrodfor said ram, a slidable plugging block closing the other end of saidchamber and slidably mounting said ram and said ramrod, the relativemotion of said ramrod and said plugging block producing an injection oflubricant under very high pressure into said chamber and an annularfeed-reservoir between said ramrod and said plugging block, saidlubricant being maintained in the plastic state and at a suitabletemperature in said reservoir.

2. A device as described in claim 1, the rear portion of said ramrodhaving a larger diametrical cross-section than the front portion of saidramrod to force lubricant out of said reservoir into said chamber whensaid plugging lock engages said extrusion container, the quantity oflubricant injected filling the space between the internal wall of saidchamber and the body to be extruded.

3. A device as described in claim 1, said ramrod moving relatively tosaid plugging block a distance equal to the displacement within saidchamber for extrusion and for a preliminary injection of a givenquantity of lubricant.

References Cited UNITED STATES PATENTS 1,321,096 11/1919 Geer 72--27l3,072,251 1/ 1963 Sauve 72--42 CHARLES W. LANHAM, Primary Examiner.

H. D. HOINKES, Assistant Examiner.

